1. Field of the Invention
The present invention relates to information handling systems having I/O subsystems, and more particularly to such information handling systems wherein input/output (I/O) subsystems include a number of I/O terminals connected to controllers which control communication between a host processor in the information handling system and the terminals.
2. Prior Art
The present invention is an improvement to the invention described in U.S. Pat. No. 4,811,284 entitled "Computer Terminal System with Memory Shared Between Remote Devices", hereinafter referred to as the '284 patent. The teachings of the above identified patent including the drawing and specification are hereby incorporated by reference into this application.
The '284 patent generally relates to a data I/O terminal system having a device controller to which displays or other I/O devices are connected by a transmission system such as individual coax lines to the respective devices and which includes a communication buffer in the remote device to receive and transmit data and control information from and to the controller via the communication link. Although the buffer is located in the device, its use is directed by the control unit for data transmission in both directions. The control unit places data at any point in the buffer and instructs the device to process it. On completion of the required operation, the device signals the controller.
The '284 patent describes in specific detail the structure and operation of apparatus on which the present invention may be executed.
However, it should be noted that the '284 patent teaches a computer terminal system in which there may be different classes of remote devices and in which each controller is structured to operate with only one class of remote device on each terminal coax line. The controller operates with other classes of remote devices on other coax lines.